diff --git a/common/ptr/ptr.go b/common/ptr/ptr.go
index 30a8efe..9315228 100644
--- a/common/ptr/ptr.go
+++ b/common/ptr/ptr.go
@@ -13,6 +13,7 @@ type Ptr[V any] interface {
 	Set(V) Ptr[V]
 	Size() int
 	Started() bool
+	Advance(int) Ptr[V]
 	Seek(int) Ptr[V]
 	Reset() Ptr[V]
 	Clone() Ptr[V]
diff --git a/common/ptr/scalar.go b/common/ptr/scalar.go
index 4171dcd..5576b56 100644
--- a/common/ptr/scalar.go
+++ b/common/ptr/scalar.go
@@ -67,6 +67,17 @@ func (p *acc[V]) Started() bool {
 	return p.started
 }
 
+func (p *acc[V]) Advance(i int) Ptr[V] {
+	if i == 0 {
+		return p
+	}
+	if p.started && i > 0 {
+		return nil
+	}
+	p.started = i >= 0
+	return p
+}
+
 func (p *acc[V]) Seek(i int) Ptr[V] {
 	p.started = true
 	return p
diff --git a/common/ptr/slice.go b/common/ptr/slice.go
index d8b5577..5d596d2 100644
--- a/common/ptr/slice.go
+++ b/common/ptr/slice.go
@@ -68,6 +68,19 @@ func (p *sptr[V]) Started() bool {
 	return p.offset >= 0
 }
 
+func (p *sptr[V]) Advance(i int) Ptr[V] {
+	p.offset += i
+	l := len(*p.seq)
+	if p.offset >= l {
+		p.offset = l - 1
+		return nil
+	}
+	if p.offset < -1 {
+		p.offset = -1
+	}
+	return p
+}
+
 func (p *sptr[V]) Seek(i int) Ptr[V] {
 	p.offset = i
 	return p
diff --git a/tests/common_test.go b/tests/common_test.go
index 4eb531c..4ce3a40 100644
--- a/tests/common_test.go
+++ b/tests/common_test.go
@@ -119,6 +119,8 @@ func PtrSliceTest(t *testing.T) {
 	t.AssertEqual(sp1.Value(), 99)
 	sp1.Next()
 	t.AssertEqual(sp1.Value(), 12)
+	sp1.Advance(-1)
+	t.AssertEqual(sp1.Value(), 99)
 	sp1.Reset()
 	t.AssertEqual(sp1.Next().Value(), 11)
 }